As shown in StrikerS (ep.13), Zest and Lutecia rescued Agito from a laboratory where illegal research was being performed on her in 0073. After burning down the lab, Zest offered Agito freedom, but Lutecia convinced him to take her with them, since Agito did not have a purpose in her life at that point.

After Signum defeats Zest near the end of the JS Incident and gives him a last moment of honor as a knight, Agito agrees to go with Signum and later goes into Unison with her to destroy the Gadget Drones.

After the JS Incident, Agito is judged for a tentative 5-month quarantine at the Midchilda South-Sea Asylum under the protection of Hayate Yagami, and an 8-month stay of execution.[3] Afterwards, Agito joins the AAS Midchilda Capital Air Force 14th-Team as Air Captain Assistant, at the rank of 3rd Ground Member.[2]

Agito also appears in StrikerS manga, though mainly in flashback of the anime series.

Agito is first seen having a meal together with the Yagami family. Like Rein, she generally appears in full-size when off from work. Though not obviously described, Agito is referred by Lutecia as her "very first old good friend". When the Yagamis makes Einhard Stratos an Ancient Belkan Device (Asteion), she is responsible for its snow leopard overcoat.

Agito appears in the prologue chapter of Force as Signum's partner. Along with Signum, she is now a member of the Special Duty Section 6. She makes her first proper appearance in chapter 3, when she and Signum investigate the ruins of the installation destroyed by Thoma Avenir and Lily-Strosek on Ruwella. Both are revealed to be in pursuit of the Hückebein, as well as the EC Divider and the Reactor (implied to be Lily). During her report to Teana, Agito expresses doubts that Thoma is associated with the Hückebein, since the equipment and the machinery are left intact and there are no fatalities.

She and Signum make their second appearance in chapter 5, when they discover Thoma and Lily just in time to save them from Cypha of Hückebein. After Cypha ignores Signum's warnings to drop her weapons, Signum engages her in aerial battle, while Agito analyzes Cypha's magical fields (and presumably informs the Port Town officials to start civilian evacuation). As soon as the analysis is complete, she enters Unison with Signum and they attack Cypha together, managing to completely sever her right arm. Agito, however, immediately notices that this has also significantly damaged Laevatein and Signum explains that its defenses are not solid enough to cut an infected body like Cypha's.

Agito is surprised to see Cypha still moving and regenerating her arm, but Signum once again explains that it is to be expected from someone in the mid-stages of Eclipse virus infection. Agito completes the "capture system" setup and informs Signum that a contact time of 0.2 seconds will be sufficient to restrict Cypha. When Cypha fully activates her Divider, the two of them prepare for another battle. Before they can engage each other again, though, Thoma's Eclipse powers awaken and Signum orders Agito to Unison Out and restrain him. This proves to be a tactical error, when Cypha effortlessly shatters Laevatein and pins Signum to the ground. Agito tries to help her master but is shot from afar with a bombardment attack. She is last seen hanging from a tree branch, heavily bruised and unconscious.

Chapter 8 reveals that Signum and Agito are still alive when the Bureau's medics get to them, despite sustaining severe injuries and losing consciousness. When Signum finally wakes up in chapter 18, Agito is already back on her feet and waiting at her master's side for her to awaken, along Hayate and Rein.

As a Device, Agito often goes into Unison with Zest in StrikerS, and later with Signum after the death of Zest. Notably, both cases result in the lord's gauntlets turning gold. Due to the high compatibility, Agito's Unison with Signum has a more dramatic effect comparing with her Unison with Zest and Signum's Unison with Reinforce Zwei. Signum's jacket disappears and two pairs of dragonfly-like flaming wings appear from her back. Signum's weapon, Laevatein, is enchanted with a permanent fire. The power of Signum's own fire-based attacks also increases drastically, e.g. she is able to completely wipe out over fifty Gadget Drones with one attack without Laevatein.

In StrikerS, Agito's usual outfit simply consists of bikini, handcuffs, waist belt and long boots. It is not known if this outfit is a Barrier Jacket (too light to be Knight Armor and too wild to be Knight Clothing) or has any defensive power.

After the JS Incident, when Agito works aside Signum in the Administrative Bureau, she casts a proper Knight Clothing, whose designs are based off the Knight Clothing of her lord, Signum.